A conventional power tool, such as e.g. a grinder, comprises a bevel gear that is provided to redirect the rotational movement from a pinion shaft rotating around a first axis to an output shaft rotating around a second axis that is substantially perpendicular to the first axis.
The bevel gear is continuously in need of lubrication. In the type of power tool to which the invention relates this may be solved in that a lubrication fluid is arranged in a fluid tight gear space that surrounds the bevel gear. In order to prevent that the lubrication fluid leaks out from the gear space, the gear space is sealed off. Hence, the gear space is a fluid tight space that is delimited by a gear housing. The gear housing is normally formed of several parts and inter alia includes two sealings, one axial sealing around the pinion shaft and one radial sealing around the output shaft. Further, both the output shaft and the pinion shaft are supported by bearings, which preferably are located as close as possible to the bevel gear.
A problem that arises in conventional power tools of this type is that especially the axial sealing around the pinion shaft is degenerated over time, such that lubrication fluid may eventually leak into the motor room and/or pass out to the area known as the reception area, e.g. the area immediately surrounding the power tool and the operator. The sealing surrounding the pinion shaft is specifically crucial as the pinion shaft rotates about five to ten times faster than the output shaft, depending on the gear ratio of the bevel gear.
Hence, there is a need for a power tool in which the life time of the sealing around the pinion shaft is prolonged and in which the overall reliability of the power tool is ameliorated.